Keep track of them for yourself, PTCAS is only for documenting them when you apply. I never saw a facility log them. The challenge may be getting in contact with the PT you shadow 2+ years from now to get them to verify the hours when you are submitting your application. Don't kill yourself over it now, you still have plenty of time. Do take into consideration though that inpatient hours, particularly in the acute hospital and acute rehabilitation settings, are typically difficult to set up, so I would plan on that taking several months. Observing in these settings as well as a couple different flavors of outpatient PT is very important for having an overall strong application.